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My Continuum build and an apples to apples comparison. LONG

01-18-2018, 09:26 PM

I wanted to take a minute to review my Continuum build and then compare it to a speaker that is what I feel the best known comparison the Stirling Broadcast LS3/5a V2 (http://www.stirlingbroadcast.net/ls35a_v2.html). I like this comparison since Jeff voiced the Continuum like the original LS3/5a. Doug - Stirling Broadcast is similar to the Continuum in that it is a clone variant as well. The Stirling Broadcast was also voiced like the original LS3/5a.

The design goals were also similar. Make a more modern LS3/5a with current drivers. Both are capable of higher SPL than the original and neither are 15ohm like the first LS3/5a.

Now some direct comparison. First Doug Stirling did secure BBC blessing to produce and call this speaker an LS3/5a. It is very very similar but, as I mentioned already, is able to play louder and does exhibit a bit more low end extension. It does have the characteristic mid-bass hump as the original.

Jeff, the way I understand had a very similar design goal. Of course he did not make this an exact duplicate as Doug with the V2 but something close with that familiar sound. Jeff also used the more modern Harbeth p3esr http://www.harbeth.co.uk/hifi-speakers/p3esr.php for inspiration. (Jeff please feel free to add, clarify or debunk what I have written )

How did Doug at Stirling Broadcast fair with his version of the LS3/5a? Extremely well. I have owned other LS3/5a and the V2 is the best I have had.

How did Jeff do? Extremely well. My version is very similar to the LS3/5a in sound but there are differences.

Let me caveat what I sat about the Continuum Jeff designed. Jeff, unlike Doug, has no control over what the end product sounds like. He does not supervise crossover assembly, nor cabinet assembly and I can tell you my build is different than Jeff’s and they will sound different.

As you can see from the pictures I decided to build my Continuum in the spirit of the BBC engineers original design. I, like Doug used 9mm Baltic Birch with Beach support framework.
My original plan was to do as Doug did and make both the from and rear panels removable. Unfortunately, due to my lack of skill and tools I messed this up and resorted to what every other LS3/5a employed. I glued the back on.

I did manage to get the baffle correct and that is screw on like other LS3/5a. It is also apparent with the grills off how similar these two are. The Continuum is a slightly larger speaker but still a bookshelf speaker. Notice I even copied the felt configuration.
Internally the likeness continues. The original spec was 2 layers of asphalt material on the top and bottom as well as one layer on the sides. Foam was used to line all but the baffle. Doug also used this recipe and so did I. However, I used a non-asphalt product. The product I used is perhaps exactly the material that you would find holding your car windshield in place.

If you are unfamiliar with the BBC reasons for using “thin” walls and Lossy cabinets was to reduce the resonant frequency (one by the less rigid 9mm walls and two by introducing some energy decoupling with screw on panels. Of course that was discovered AFTER they used thin walls to reduce weight and make the portable monitor lighter.

BBC engineers also found by adding mass via bitmum reduced the amplitude. So the theme was shift the freq down and then attenuate it.

Alan Shaw at Harbeth supports this design philosophy and uses it with his best in class p3esr.

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The sound: Let me use shorten the names to make my life easier. I will refer to the Doug Stirling LS3/5a V2 as V2 and the Continuum as CON. Furthermore CON refers to MY SPECIFIC BUILD only.

First let me just talk about the general sound that both of these speakers possess, what they are good at and what they lack.

The LS3/5a grew into a cult speaker due to it’s very engaging midrange quality. It does not wow you with dynamics, nor bass definition. These traits along make it a better vocal, instrumental, acoustic treat but a disappointment if cranking AC/DC is your thing.

The original BBC engineers employed a 160hz bass “hump” in the crossover design that while deviates from a “flat” response created a full, rather plump quality to the bass that the LS3/5a. The frequency response then dips until nearly 400hz to which it again climbs and peaks near 1200hz. This combination gives a full, at times thick sound with a vocal fullness that makes certain music very pleasing.

The BBC spec also had careful component matching part of the original design. This, along with a narrow baffle contribute to the great imaging characteristic all LS3/5a’s possess.

Ok with that out of the way how do these two examples compare?

V2: Nailed the LS3/5a sound. It really should since it has everything going for it. Doug and Derek Hughs (Derek’s Father was one of the BBC engineers and also went on to create Spendor loudspeakers where Derek worked as Technical director ) had access to the original LS3/5a BBC 001/002 as a reference. Derek himself designed and selected components for Doug’s V2. The crossover is of a high quality, and each speaker is matched with a 3 way selector on the crossover (in 0.5db increments.)CON Nailed it -almost. A/B comparisons of the V2 and CON quickly reveal these two examples are at the very least brothers. The CON does have a family resemblance in the midrange. You certainly could be fooled into thinking this is an LS3/5a. Doug did engineer a roughly 160hz hump as the original yet it does not seem to be quite as pronounced as the V2. There is the characteristic dip after that but the CON does not go onto peak again around 1200hz. This flatter response does contribute to a little less fullness with certain music such as male vocals. It does tend to sound a little less full without this second “hump.” However, the speaker does not sound thin either.

V2: The bass on any LS3/5a is non-existent down past around 100hz. So the 160hz hump helps fill in the perception of bass while yielding a tad more output below 100hz.CON: There is a little less hump in the hump here so comparatively the CON is slightly less “boosted” in the 100hz region and sounds a little less full to my ear.

V2 The midrange is smooth, full and plump (yes goofy words that happen to fit the sound). The hump around 1200hz seems to round out the package.CON Jeff nailed the midrange with the CON. I remember reading that he chose the Aurum Cantus unit specifically for this sound quality. This is perhaps the most important feature of the CON

V2 Treble and upper extension on the V2 is perhaps slightly better than the original. Doug used Seas and Scanspeak drivers and it is perhaps these units with the fabric tweeter dome that lends to this quality. The original LS3/5a, to my ears, was a little rough on top where the V2 excels.CON Jeff worked, I feel with more constraints, using a Dayton Aluminum dome tweeter and the Aurum Cantus Woofer. Both units are of high quality but unlike the V2 were not produced specifically for the CON. I do not think the Dayton tweeter is quiet is smooth as the fabric tweeter the V2 uses. I hear just a tad more sibilance with the CON.

The imaging on the V2 is impeccable and true to the original. The CON also does a good job at this and when, positioned well, disappear while the artists and instruments take front and center.

Both the V2 and CON are both very enjoyable speakers that excel at producing a buttery smooth midrange. They do sound remarkably similar across the entire audio spectrum. By comparison the V2 sounds a little BIGGER than it is and the CON sounds like I would expect coming from a sealed box of its size. The slightly larger peak at 160hz is likely the reason for this difference.

The CON with a little flatter frequency response, can at times, sound a little more open and relaxed as though it is not trying to hard to sound good. The V2 with a more pronounced hump can sound a little congested or bunched up (Sorry but I just don’t have the terminology down .) Some music may sound better with the CON compared to the V2 and vice vera.

If I could only keep one set I would keep the V2. Why? For most of what the LS3/5a is known for the V2 is slightly truer to the design and I like having that as a reference. Does it sound better than the CON? I can’t answer that yet. I THINK that 90% of the time they are interchangeable. That 10% however is where the V2 shines. It does not reveal itself as easily. I sense a small void in the lowest bass of the CON where the V2 has a little magic in that the voids are less perceptible to my ear. That is to say I notice the lack of extension a little more on the CON than with the V2.

Both the V2 and the CON are, in my opinion, faithful to the original LS3/5a sound and both are better in some ways. Both can play louder with less compression for sure.

I need to say the front end I am using borders on terrible (Sugden CD player and Yamaha receiver.) I have had much better front ends and a highly damped amplifier with a robust PSU could change my opinions for sure. Until I build up a new front end however this is what I have to report.

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After some more listing, the continuums do throw of a nice image and disappear very well. I find they have slightly less weight in piano than the V2 above. They have a slightly different tonal quality but they sound great.

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Interesting write-up. Thanks for posting your thoughts. I know it's not part of the original setup, but if you added a sub, I bet it would make the difference between the V2 and CON even more difficult to determine. I love my continuums. The dip between the 160hz hump and where it flattens out at 400hz really balances out boundary reinforcement of typical monitor placement on stands relatively close to the front wall.

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Interesting write-up. Thanks for posting your thoughts. I know it's not part of the original setup, but if you added a sub, I bet it would make the difference between the V2 and CON even more difficult to determine. I love my continuums. The dip between the 160hz hump and where it flattens out at 400hz really balances out boundary reinforcement of typical monitor placement on stands relatively close to the front wall.

Thanks Bjaurello, I actually am going to do just that. I just started thread on recommendations for that. I am going to do the CSS SDX10 would be a good choice. I even thought about doing what Jeff wrote about, a 3 way design with those woofers, but I really need to be able to move the mains for proper listening (I don’t have a great room.) I am sure that the combo will be very very nice and for the total money even better.

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I keep tinkering with them as time allows. I have been trying to figure out a bit of a mid-bass issue with them likely due to my room or perhaps my box. Today I opened them up, and added single of 1”x”1 beach to act as a brace without taking too much box volume. Instead of glueing it I cut it so that I could maneuver it into place on top of the sound deadening (RAAMmat.) It is compressed in there and then I used more RAAMmat around the wood to keep if from slipping. KEF braced the LS50 but the braces are not glued but rather attached with a viscoelastic material. The butyl in the RAAMmat should have some damping effect on the brace too.

Then I switch out all of the dacron I had on the walls with 1” thick rigid fiberglass.

The result was the knuckle rap test is better with the brace. The sound however is worse Too much fiberglass. The now sound a little thin and tight. It did however attenuate some of the hump or thump as that is kind of what it sounded like. I liken it to tapping on a watermelon.

Don’t read into this that the Continuum sounds like thumping a watermelon. It does not . And this is my box, my stuffing, my room and my result. As the saying goes, results may vary. For me it is part of the fun. I get to play and understand the outcome of my experiments.

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I think I have it now! I removed all the stuffing save for one piece of Dacron toward the back of the speaker. Nothing on the walls at all except the RAAMmat.

The single stick brace did a ton to the side wall resonance and the result of that is clearly better imaging (the speakers disappear better) and they were no slouch at that to start. The removal of most of the stuffing did a lot to open them up. Yesterday’s experiment showed me they did not need more but rather less stuffing. Now they more full sounding with better defined bass in the region I was having a problem. I don’t think I can do any more with this particular speaker/box combo.

Now of course I may build that great TL box for them. That would be fun.

As it is now these Continuums are extremely close to my Stirling Broadcast LS3/5a. The Stirling’s may still have a slight edge but it is very slight. Again, it is unfair to compare a speaker with Scan-speak and Seas driver with a similar designed speaker with more price point drivers. The cost differential is sometime like a factor of 5 so I cannot conclude anything other than the Continuum being a huge value.